[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 041448
TCDAT4

POST-TROPICAL CYCLONE HERMINE DISCUSSION NUMBER  29
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092016
1100 AM AST SUN SEP 04 2016

Hermine continues to have the structure of a post-tropical cyclone,
with practically all of the deep convection well removed to the
north-northeast of the center.  An Air Force reconnaissance aircraft
measured peak surface winds near 60 kt, and that value is used for
the advisory intensity.  Since the cyclone is over warm
waters and the vertical shear may decrease somewhat during the next
couple of days, some partial transition back to a tropical cyclone
is possible.  However, this is not explicitly indicated in the
official forecast.  In any event, the intensity of the system
should be at or near hurricane force over the next 48 hours or so.

Based on center fixes from the aircraft, the initial motion is
060/9 kt.  A mid-tropospheric short wave trough will approach
Hermine within the next day or so, and the global models forecast
this vorticity maximum to merge with Hermine.  This interaction
is expected to cause the post-tropical cyclone to move
northeastward, then northward, and then north-northwestward during
the next 36 hours or so.  Since the center has already moved a
little to the east of the previous track, the official forecast has
been adjusted eastward.  Later in the forecast period, the system
should move east-northeastward, and away from the northeastern
United States.  The official track forecast is somewhat to the west
of the latest multi-model consensus.

The slow motion and large wind field associated with Hermine will
result in a long duration of hazardous conditions along much of the
mid-Atlantic coast extending into southern New England through the
holiday weekend and into midweek.

FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 37.2N  69.6W   60 KT  70 MPH
 12H  05/0000Z 37.6N  69.4W   60 KT  70 MPH...POST-TROPICAL
 24H  05/1200Z 38.3N  69.8W   60 KT  70 MPH...POST-TROPICAL
 36H  06/0000Z 38.7N  70.0W   65 KT  75 MPH...POST-TROPICAL
 48H  06/1200Z 39.0N  70.0W   65 KT  75 MPH...POST-TROPICAL
 72H  07/1200Z 40.0N  68.0W   60 KT  70 MPH...POST-TROPICAL
 96H  08/1200Z 41.0N  66.0W   55 KT  65 MPH...POST-TROPICAL
120H  09/1200Z 42.0N  60.5W   50 KT  60 MPH...POST-TROPICAL

$$
Forecaster Pasch

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